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class SF::Image
inherits Reference #

Class for loading, manipulating and saving images

SF::Image is an abstraction to manipulate images as bidimensional arrays of pixels. The class provides functions to load, read, write and save pixels, as well as many other useful functions.

SF::Image can handle a unique internal representation of pixels, which is RGBA 32 bits. This means that a pixel must be composed of 8 bits red, green, blue and alpha channels -- just like a SF::Color. All the functions that return an array of pixels follow this rule, and all parameters that you pass to SF::Image functions (such as load_from_memory) must use this representation as well.

A SF::Image can be copied, but it is a heavy resource and if possible you should always use [const] references to pass or return them to avoid useless copies.

Usage example:

# Load an image file from a file
background = SF::Image.from_file("background.jpg")

# Create a 20x20 image filled with black color
image = SF::Image.new(20, 20, SF::Color::Black)

# Copy image1 on image2 at position (10, 10)
image.copy(background, 10, 10)

# Make the top-left pixel transparent
color = image.get_pixel(0, 0)
color.a = 128
image.set_pixel(0, 0, color)

# Save the image to a file
image.save_to_file("result.png") || error

See also: SF::Texture

Class methods#

.from_file(*args, **kwargs) : self #

Shorthand for image = Image.new; image.load_from_file(...); image

Raises InitError on failure

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.from_memory(*args, **kwargs) : self #

Shorthand for image = Image.new; image.load_from_memory(...); image

Raises InitError on failure

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.from_stream(*args, **kwargs) : self #

Shorthand for image = Image.new; image.load_from_stream(...); image

Raises InitError on failure

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.new #

Default constructor

Creates an empty image.

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.new(*args, **kwargs) : self #

Shorthand for image = Image.new; image.create(...); image

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Methods#

#copy(source : Image, dest_x : Int, dest_y : Int, source_rect : IntRect = IntRect.new(0, 0, 0, 0), apply_alpha : Bool = false) #

Copy pixels from another image onto this one

This function does a slow pixel copy and should not be used intensively. It can be used to prepare a complex static image from several others, but if you need this kind of feature in real-time you'd better use SF::RenderTexture.

If source_rect is empty, the whole image is copied. If apply_alpha is set to true, the transparency of source pixels is applied. If it is false, the pixels are copied unchanged with their alpha value.

  • source - Source image to copy
  • dest_x - X coordinate of the destination position
  • dest_y - Y coordinate of the destination position
  • source_rect - Sub-rectangle of the source image to copy
  • apply_alpha - Should the copy take into account the source transparency?
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#create(width : Int, height : Int, color : Color = Color.new(0, 0, 0)) #

Create the image and fill it with a unique color

  • width - Width of the image
  • height - Height of the image
  • color - Fill color
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#create(width : Int, height : Int, pixels : Pointer(UInt8)) #

Create the image from an array of pixels

The pixel array is assumed to contain 32-bits RGBA pixels, and have the given width and height. If not, this is an undefined behavior. If pixels is null, an empty image is created.

  • width - Width of the image
  • height - Height of the image
  • pixels - Array of pixels to copy to the image
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#create_mask_from_color(color : Color, alpha : Int = 0) #

Create a transparency mask from a specified color-key

This function sets the alpha value of every pixel matching the given color to alpha (0 by default), so that they become transparent.

  • color - Color to make transparent
  • alpha - Alpha value to assign to transparent pixels
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#dup : Image #

Returns a shallow copy of this object.

This allocates a new object and copies the contents of self into it.

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#finalize #

Destructor

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#flip_horizontally #

Flip the image horizontally (left <-> right)

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#flip_vertically #

Flip the image vertically (top <-> bottom)

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#get_pixel(x : Int, y : Int) : Color #

Get the color of a pixel

This function doesn't check the validity of the pixel coordinates, using out-of-range values will result in an undefined behavior.

  • x - X coordinate of pixel to get
  • y - Y coordinate of pixel to get

Returns: Color of the pixel at coordinates (x, y)

See also: pixel=

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#load_from_file(filename : String) : Bool #

Load the image from a file on disk

The supported image formats are bmp, png, tga, jpg, gif, psd, hdr and pic. Some format options are not supported, like progressive jpeg. If this function fails, the image is left unchanged.

  • filename - Path of the image file to load

Returns: True if loading was successful

See also: load_from_memory, load_from_stream, save_to_file

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#load_from_memory(data : Slice) : Bool #

Load the image from a file in memory

The supported image formats are bmp, png, tga, jpg, gif, psd, hdr and pic. Some format options are not supported, like progressive jpeg. If this function fails, the image is left unchanged.

  • data - Slice containing the file data in memory

Returns: True if loading was successful

See also: load_from_file, load_from_stream

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#load_from_stream(stream : InputStream) : Bool #

Load the image from a custom stream

The supported image formats are bmp, png, tga, jpg, gif, psd, hdr and pic. Some format options are not supported, like progressive jpeg. If this function fails, the image is left unchanged.

  • stream - Source stream to read from

Returns: True if loading was successful

See also: load_from_file, load_from_memory

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#pixels_ptr : Pointer(UInt8) #

Get a read-only pointer to the array of pixels

The returned value points to an array of RGBA pixels made of 8 bits integers components. The size of the array is width * height * 4 (size().x * size().y * 4). Warning: the returned pointer may become invalid if you modify the image, so you should never store it for too long. If the image is empty, a null pointer is returned.

Returns: Read-only pointer to the array of pixels

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#save_to_file(filename : String) : Bool #

Save the image to a file on disk

The format of the image is automatically deduced from the extension. The supported image formats are bmp, png, tga and jpg. The destination file is overwritten if it already exists. This function fails if the image is empty.

  • filename - Path of the file to save

Returns: True if saving was successful

See also: create, load_from_file, load_from_memory

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#set_pixel(x : Int, y : Int, color : Color) #

Change the color of a pixel

This function doesn't check the validity of the pixel coordinates, using out-of-range values will result in an undefined behavior.

  • x - X coordinate of pixel to change
  • y - Y coordinate of pixel to change
  • color - New color of the pixel

See also: pixel

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#size : Vector2u #

Return the size (width and height) of the image

Returns: Size of the image, in pixels

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